Study On Preparation And Properties Of Water-permeable Ceramic Bricks Using Ionic Rare Earth Tailings

Rare earth resources rich in our country, while the rare earth tailing after exploited have great influence to the ecological environment and economic development of local and nearby areas, at the same time is a waste of resources. Water permeable ceramic bricks, as a new type of urban ground decorates material, have well permeability and water retention, and can effectively relieve underground water level decline and cities "heat island" effect from urban surface hardening.In the present work, water-permeable bricks were prepared by mainly using the recycled South Jiangxi rare earth tailing from which kaolin was separated, and using the appropriate content of high temperature adhesive by compression moulding. Grain composition of rare earth tailing and type and proportion of high temperature adhesive on performance of water-permeable ceramic bricks were studied. And on this basis, through the improvement of preparing process, such as molding pressure, firing temperature and soaking time, the water-permeable ceramic bricks support with high bending strength, high compressive strength, well permeation coefficient and water retaining property. It not only provides a new way for rare earth tailing resources utilization, but also produces social benefits and application value in the day sustainable development and environmental protection are more and more important.At first the method of adding pore-forming agent and the method of particle stacking were compared, ultimately water-permeable ceramic bricks is determined prepared by using the the method of particle stacking. The design of particle size gradation is the basement and key point to obtain water-permeable ceramic bricks support with high permeation coefficient, high water retaining property. The final grain size distribution proportion is determined, it is A sand 19wt%, B sand 45wt%, C sand 24.3wt%, D sand 11.7wt%. At the moment, the overall utilization of recycled rare earth tailing is 86.1%.Then adjust the type and proportion of high temperature adhesive through the single factor experiment and separately study the influence on water-permeable ceramic bricks of low temperature sand, black talc and limestone. Then the three types of high temperature adhesives are comprehensive analyzed by using the method of orthogonal experiment, which determined that the best proportion of high temperature adhesive:low temperature sand 4wt%, black talc 4.5%, limestone 10wt%. When research on the usage of rare earth tailing in preparing water-permeable ceramic bricks, it finds that the maximum usage of rare earth tailing is 79 wt%.Base on these research, we can discover that the permeation coefficient of water-permeable ceramic bricks mainly determined by the aperture inside from the research of the preparation process conditions. When the firing temperature increased from 1200℃ to 1260℃, the bending strength increased gradually though the porosity decreased gradually, the aperture approximately is 0.8mm at 1240℃, which show the maximum permeation coefficient. The influence soaking time is the same to firing temperature, which show the maximum permeation coefficient when the soaking time is 30min. When moulding pressure increased, the compactness of water-permeable ceramic bricks has improved, and then the bending strength increased, the aperture lessened, at last lead to the decrease of permeation coefficient. Optimized preparation condition is firing temperature 1240℃, soaking time 30min, moulding pressure 12MPa. On this condition the bending strength of water-permeable ceramic bricks is 5.5MPa, compressive strength is 45.5MPa, the permeation coefficient is permeation coefficient, water-retaining property is 1.28g/cm2.